The present invention relates generally to metal strip edge and, more particularly, to a method and apparatus for monitoring and inspecting in real time various characteristics of the strip edge.
Strip metal is a commodity that is commonly produced by the metals industry. Typically, various operations must be performed on the metal strip before the strip can be processed into one or more final products. Operations typically performed on metal strip include edge-trimming, slitting, shearing and stamping operations.
In a slitting operation, a wide, metal strip is cut into any suitable number of narrower strips. Likewise, in an edge-trimming operation, a metal strip of, usually, non-uniform width is trimmed to a desired width. Slitting and edge-trimming operations are typically performed by rotary cutting knives mounted, respectively, above and below the strip at a desired location for cutting or trimming same. In the above-noted operations, new edges for the metal strip are produced thereby.
It is important for a number of reasons to obtain high-quality strip edges from the above-noted operations. For example, low-quality edges may subsequently crack or rust, or cause subsequent coating or welding problems, or reduce the "fit and finish" of the strip, all of which results in increased processing costs and scrap rates.
In slitting and edge-trimming operations, the quality of the edge is usually dependent on the setting or positioning of the knives. For example, the upper knife can be adjusted vertically to create a desired amount of overlap with the lower knife. In addition, the lower knife can be adjusted horizontally to adjust the amount of clearance between the upper and lower knives.
Customarily, the knives are initially positioned and subsequently adjusted according to settings which, from empirical experience with strip of the same thickness and metallurgical composition, are thought to be correct. In addition, the edges of strip produced by the knives are periodically manually and visually inspected to determine whether the knives are properly set and otherwise in good working order (e.g., the knife edges are sharp and defect-free).
Because strip edge inspection has only been done periodically and not in real time, a number of strip metal coils may be processed before a problem with one or more of the knives is detected. This can lead to many of the strip metal coils being scrapped or reworked if the edge quality has become unacceptable.